Corner guards are commonly attached to the lower exterior rounded corners of mattress foundations or "box springs", to protect the fabric which covers the foundation and foundation frame. Such corner guards typically extend in two dimensions about each corner; over a small area of the vertical side of the curved corner of the foundation, and over a small area of the flat bottom of the foundation adjacent the corner. Foundation corner guards have heretofore been made only of flexible plastic material, molded with a generally flat sidewall and attachment tabs which extend perpendicularly from the side wall, as shown in FIG. 1. Flexible plastic corner guards are installed upon the foundation by wrapping or bending the flat sidewall around the curved vertical wall at the bottom edge of the corner, and attaching the tabs which extend perpendicularly from the vertical wall against the underside of the foundation by fasteners driven through the tabs. In plastic corner guards of this type, it is only the attachment of the tabs to the underside of the frame at the corner that retains the vertical wall in the curved configuration. When the tabs are detached by breakage or failure of one or more of the fasteners, the vertical wall readily returns to an unbent, flat shape or is completely detached.
Other disadvantages of plastic corner guards and the associated methods of manufacture and attachment are the difficulties of getting the flat piece to tightly conform to the curved vertical wall surface of the foundation corners, and the resultant sloppy appearance of an ill fit. The perpendicular foundation of the attachment tabs are the only support to keep the vertical wall upright and are structurally inadequate to withstand forces applied to the top edge of the curved upright wall of the guard. Therefore, the curved wall of the guard is easily deflected away from the corner. Even guards which appear to conform to the curve of the corner at the factory can be easily detached, broken or warped due to inherent weakness of the material and by the post-molding bending, or as a result of detachment or loosening of a fastener. This frequently occurs during shipping and handling. Because plastic guards then immediately deform from the curved corner of the foundation, the foundation cannot be placed into a supporting bed frame without crushing and further deforming the guard. Also, the required bending precludes application of any type of coating or finish to the exterior of the guard which would crack when the guard is bent around the curved corner.